High-Speed Pulsed Measurements for Radar
Modern radars are multi-functional and multimode; using active antennas allowing “instantaneous” beam pointing and interlacing different modes, like the track-while-scan mode of airborne radars. Such radars use fast switching of different pulse patterns. Classical techniques for distance ambiguity solving use staggered PRF techniques. Frequency diversity increases the range. Pulse compression, which employs an intra-pulse frequency modulation (chirp), is another known technique to increase the distance resolution.
Independent of design and complexity, all radar systemsrely on processing raw data from the basic radar pulse. Testing the basic “analog” radar pulse performance involves the following pulse parameter measurements:
- Timing: Pulse repetition interval or pulse repetition frequency, pulse width
- Frequency: Frequency in pulse, frequency modulation in pulse
- Power: Power in pulse
Full testing of these waveform parameters at the development/qualification stage generally required sophisticated and expensive test instruments, like real-time spectrum analyzers and high-bandwidth oscilloscopes. Now, the cost-effective Pendulum CNT-90XL Microwave Counter/Analyzer can do the job, due to ultrafast measurements (250,000 samples/s). It measures fast changes in PRI/PRF and pulse-width in radar pulses down to 30 ns width. It further measures frequency in pulses down to 100 ns and power in pulse down to 20 us. The CNT-90XL can also provide the intra-pulse frequency profile. It is possible to measure frequency in each 20 ns slice of the pulse.
The CNT-90XL is available in four frequency input ranges (27/40/46/60 GHz). A battery option allows mains free operation for field applications. The software TimeViewTM provides enhanced Modulation Domain Analysis. Another key feature is the graphic display of measured parameters. With the introduction of Pendulum CNT-90XL Pulsed RF, Spectracom brings an affordable instrument (< $10,000) to the radar community, allowing high speed pulse measurement of all time/frequency parameters, supporting modern radars where pulse patterns change rapidly.